Supplementary cementing assembly for subaqueous wells



June. 4, 1968 E. LEoNHARo-r, JR 3,386,505

SUPPLEMENTARY CEMENTING ASSEMBLY FOR SUBAQUEOUS WELLS Filed June 8. 1966 ATTORNEY United States Patent 3,386,505 SUPPLEMENTARY CEMENTING ASSEMBLY FR SUBAQUEOUS WELLS Ernst Leonhardt, Jr., Celle, Germany, assigner to Mobil @il Corporation, a corporation of New York Filed .lune S, 1956, Ser. No. 556,219 8 Claims. (Cl. 166-.5)

This invention relates to a method and apparatus for insuring that a string of casing is completely cemented within a subaqueous wellbore and, more particularly, to apparatus for the supplementary cementing of a subaqueous well casing through the annulus thereof.

Production of oil and/or gas located beneath the continental shelves, and the contemplated extension of these efforts to the continental slopes, has given rise to various problems not usually existing in connection with onshore completions. When drilling an offshore well, a preliminary borehole is usually drilled to from fifty to about two hundred feet in depth for settiny the conductor pipe. After the conductor pipe has been set in the preliminary borehole, the hole is drilled another several hundred feet, ranging from about six hundred to a thousand feet, and a surface casing is then set inside the larger conductor pipe. It is to be understood that this step may vary to a large extent depending upon the Circumstances. For example, if a troublesome water sand were to be encountered at a depth of two hundred feet or more, the preliminary borehole would have had to be drilled to a point where this formation could be sealed off. Usually the depth to which the borehole is drilled at the second stage would be dictated by the depth of the `water formations which had to be sealed olf.

After the borehole is drilled further and the surface casing set, cement is pumped down the center of the surface casing and is forced up through the annulus between the casing and the conductor pipe until it overflows at the upper end. The cement is then allowed to set. The result is a tubular passage having two metal walls separated by a cement wall. Although cement may be forced through the area between the conductor pipe and the preliminary borehole, in many cases, particularly when the conductor pipe is jetted into a formation of unconsolidated sands, the sands tend to collapse around the pipe and hold it by friction.

lf the conductor pipe is not cemented in place and the cement liner or wall between the conductor pipe and the surface casing has voids, corrosion due to the deleterious effect of salt water on the outer metal conductor pipe can result in damage to the conductor pipe which will result in leakage into the completed well. An incomplete cement job, one in which the cement does not rise completely to the surface of the conductor casing, can lead to other problems as well, such as cracking of the conductor pipe and the surface casing caused by excessive -undarnped vibrations and lack of support. Particularly where there is more than one formation being tapped, it is necessary to be especially careful during the cementing operation to prevent voids. At offshore sites, with wells that are brought back to the surface by marine riser pipes, the cementing job must be done with eXtra care due to the vibrations that can be set up in the riser pipe, between the marine bottom and the surface of the body of water, and which can easily crack a poorly cemented casing.

If the cement does not rise to the surface, in the annulus, the situation may be rectified by pumping the cement under higher pressure. This solution is not desirable in areas of unconsolidated formations or lost circulation, and an alternative solution is to dump the cement directly down from the upper end of the annulus. In off- "ice shore wells, this is easier said than done. Particularly when drilling in deeper water, over two. hundred feet, the depth limit of a diver at the present time, it would be ditlcult to reach the marine bottom. Furthermore, it is not always easy to see what is happening at the mudline or marine bottom. It is dilicult to ascertain if cement, pumped down through the annulus, comes back up .to the marine bottom; and if it comes back up, when it comes back up. Therefore, either too little or too much cement may be pumped into such a subaqueous well. Although television cameras have been used with some success in marine operations, such devices are not always successful due to the murky condition of the water at times.

Therefore, it is an object of the present invention to provide a method and apparatus for performing a supplementary cementing operation in a subaqueous well.

Another object of this invention is to provide apparatus for permitting an operator, located above the surface of a body of water, to be aware of whether the casing annulus of the subaqueous well has filled with cement.

Other objects and advantages of the invention will become apparent from the following description when taken with reference to the accompanying drawings, wherein is shown a preferred embodiment of the invention:

FIGURE 1 is a sid elevational view of a surface casing being lowered into a subaquecus Wellbore in which a conductor pipe has been previously cemented in place; and

FIGURE 2 is a schematic representation, in cross section, of the upper end of the conductor pipe illustrating, in detail, a landing collar of the present invention affixed to the surface casing.

Now referring to FIGURE l, a floating offshore platform 1t?, having a deck 12 supported above the surface 14 of a body of water by a plurality of buoyant legs 16, has a derrick 18 mounted on the deck 12 for drilling into the subaqueous formations beneath the marine bottom Ztl. A drill string 22 is suspended in the derrick 18 by means of a swivel 24, and depends through a rotary table 26 and the deck 12. At the stage of drilling a subaqueous well shown in this figure, a preliminary borehole 28 has been drilled or jetted into the marine bottom and a conductor pipe 30 has been cemented thereinto. After the cement liner 32 between the borehole 28 and the conductor pipe 30 had set, the borehole was drilled further for the insertion of a surface casing 34. As shown, the surface casing 34 is being lowered into the wellbore, suspended from the drill string 22, on a releasable J connector 36. A circumferential landing collar 38 is aiTiXed to the surface casing to locate axially the surface casing 34 with respect to the conductor pipe 30.

After the operation shown in FIGURE l has been completed, cement is injected down through the drill pipe 22 and the surface casing 34 until it rises up through the annulus between the surface casing 34 and the well bore in the lower section, and the surface casing 34 and the conductor pipe 30 in the upper section, to seal completely the surface casing 34 in the underlying formations.

Now referring to FIGURE 2, the surface casing 34 is positioned in the conductor pipe 30, protruding from the marine bottom 20, by the landing collar 38 which engages the upper end of the conductor pipe 30 with a plurality of snaplatch devices 40. The snaplach devices 40 each consist of a detent 42 slidably mounted in a detent holder 44 and outwardly biased by a compression spring 46 trapped behind the detent 42 in its holder 44. The snaplatch devices 40 are equally spaced around the landing collar 38 to coact with a circumferential groove 48 formedv in the upper end of the conductor pipe 30.

Each detent 42 has a cam face 50 permitting the detents 42 to be drivenl radially inward as the landing collar 38 passes the upper end of the conductor pipe 30, the detents 42 springing outwardly again into engagement with the groove 4S to lock permanently the landing collar 3S in place. Spaced radial guide fins S2 are aflixed to the lower end of the landing collar 38 to center the surface casing 34 within the upper end of the conductor pipe 36 as the casing 34 is lowered thereinto. A vertical passage 54 extends through the landing collar 38 and has a cementing pipe 56 screwed into the lower end thereof and depending down into the annulus 58 formed between the casing 34 and the conductor pipe 30. A vertically oriented stab-in connection 60, fixed in the upper end of the landing collar 3S, is in operative engagement with the passage 54. A grout line 62 is slidably strapped to the drill pipe 22 (FIGURE l) and extends upward to the platform 10, the lower end of the grout line 62 being stabbed into the connection 6i) in the landing collar 38 and held in a fluid-tight relationship by circumferential seals 64.

If the primary cementing operation, through the drill pipe 22, is not fully satisfactory, the cement not rising to the top of the annulus 58, cement is then pumped from the deck 12, above the surface, through the grout line 62, the tubular passage 54, and the cementing pipe 56 into the annulus 58. After the termination of the cementing, the grout line 62 is withdrawn from the landing collar 38 by applying a vertical force from the deck 12 to pull it out of the stab-in connection 60. The drill pipe 22 is then turned to release the I connector and is withdrawn. The well is drilled further through a marine riser pipe (not shown) extending from the surface casing to the platform or by means of an open drill pipe (not shown) extending through a receiver mounted on the upper end of the surface casing 34.

The landing collar 38 may be solid as shown in FIG- URES 1 and 2 or it may consist merely of spaced radial webs or spokes interconnecting a hub and a peripheral rim for centering and axially locating the surface casing 34 with respect to the conductor pipe 30. The open type of landing collar is desirable if the operator at the surface can remotely observe, through a television receiver (0r with the aid of a diver), whether the cement has or has not reached the upper end of the annulus 58 by looking down through the open spaces in the landing collar. If the landing collar 38 is solid, a relief passage 66, bridging the collar 38, would -be necessary to allow the escape of any trapped drilling returns, or other well fluids from prior operations. The relief passage 66 would include a one-way valve 68 for permitting the trapped tiuids to be driven up out of the collar and not allowing sea water to come back in. A gravity valve 70 could also be included in the bridging passage to allow the drilling uids to pass up through, but not grout or cement. If the landing collar 38 were solid as discussed just above, the operator on the surface would be able to ltell when the cement had reached the landing collar by the wells refusal to accept any more cement through the grout line 62.

Although the present invention has been described in connectin with details of the specific embodiment as shown herein, it is to be understood that such details are not intended to limit the scope of the invention. The

terms and expressions employed are used in a descriptive and not a limiting sense and there is no intention of excluding such equivalents, in the invention described, as fall within the scope of the claims. Now having described the apparatus and method herein disclosed, reference should be had to the claims which follow.

What is claimed is:

1. In the cementing of a surface casing into a subaqueous well having a conductor pipe set in the upper end thereof, apparatus comprising a circumferential landing collar fixed to the surface casing to coact with a axially said surface casing with respect to said conconductor pipe set in a subaqueous wellbore to locate ductor pipe; and a vertically oriented stab-in connection in said landing collar in operative engagement with a first passage extending through said landing collar whereby a grout line strapped to a drill string, lowering said surface casing into said conductor pipe, has its lower end in said stab-in connection forming a releasable operative connection with an annulus formed between said surface casing and said conductor pipe.

2. Apparatus as recited in claim 1 wherein said landing collar comprises a hub and a rim, said hub being aliixed to said surface casing, said rim being aixed in relation to said hub by a plurality of spaced axial spokes, and adapted to coact with the upper end of a conductor pipe set in a subaqueous wellbore to locate axially said surface casing whereby fluid trapped within said annulus during cementing may escape out of said annulus between said spokes.

3. The apparatus of claim 2 wherein there is a cementing pipe depending from said landing collar and operatively connected to said first passage whereby cement injected directly into said annulus would enter the annulus below the upper end thereof.

4. The apparatus of claim 1 wherein said landing collar is a solid element which substantially seals the upper end of a conductor pipe when locating said surface casing therewithin.

5. The apparatus of claim 4 wherein there is a second passage extending through said landing collar and a oneway valve means in said second passage for preventing water in a surrounding body of water from entering the subaqueous well through said landing collar.

6. The apparatus of claim 1 wherein there is means for automatically permanently locking said landing collar in a conductor pipe, said locking means consisting of a plurality of outwardly spring-biased detents, and a lower cam face on each detent formed so as to cause the detent to be driven radially inward, into said landing collar, as said landing collar comes into contact with the upper end of said conductor pipe.

7. The apparatus of claim 6 wherein said locking means further comprises a circumferential groove within the upper end of the conductor pipe with which said landing collar is to coact, whereby said detents will be biased outwardly into said groove to lock permanently said landing collar in said conductor pipe.

8. The apparatus of claim l wherein said surface casing is lowered into a conductor pipe of a subaqueous well from an above-surface platform; a drill string suspended from said platform; a releasable connection between said surface casing and said drill string; and a grout line extending from said above-surface station to said landing collar strapped to said surface casing, said grout line being stabbed into said stab-in connection in said landing collar to establish a path for cement to be injected directly into said annulus.

References Cited UNITED STATES PATENTS 2,239,531 4/1941 Laurie 166-21 2,972,379 2/1961 Brown 166-46 2,989,121 6/1961 Brown 166-46 3,080,922 3/1963 Mater 166-46 X 3,089,542 5/1963 Raulins 166-75 X 3,155,175 11/1964 Johnson 175--7 3,189,099 6/1965 Otteman et al. 166-5 3,285,337 11/1966 Johnstone et al. 166-.5 3,299,953 1/1967 Bernard 166-21 3,347,319 10/ 1967 Littlejohn 166-27 CHARLES E. OCONN ELL, Primary Examiner.

R. E. FAVREAU, Examiner.

Edward M. Fletcher, J r.

Attesting Officer UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 3,386,505 June 4, 1968 Ernst Leonhardt, Jr.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 26, "sid" should read side Column 4, lines l and 2, cancel "axially said surface casing with respect to said conconductor pipe set in a subaqueous wellbore to locate" and insert conductor pipe set in a subaqueous wellbore to locate axially said surface casing with respect to said con- Signed and sealed this 14th day of October 1969.

Commissioner of Patents 

1. IN THE CEMENTING OF A SURFACE CASING INTO A SUBAQUEOUS WELL HAVING A CONDUCTOR PIPE SET IN THE UPPER END THEREOF, APPARATUS COMPRISING A CIRCUMFERENTIAL LANDING COLLAR FIXED TO THE SURFACE CASING TO COACT WITH A AXIALLY SAID SURFACE CASING WITH RESPECT TO SAID CONCONDUCTOR PIPE SET IN A SUBAQUEOUS WELLBORE TO LOCATE DUCTOR PIPE; AND A VERTICALLY ORIENTED STAB-IN CONNECTION IN SAID LANDING COLLAR IN OPERATIVE ENGAGEMENT WITH A FIRST PASSAGE EXTENDING THROUGH SAID LANDING COLLAR WHEREBY A GROUT LINE STRAPPED TO A DRILL STRING, LOWERING SAID SURFACE CASING INTO SAID CONDUCTOR PIPE, HAS ITS LOWER END IN SAID STAB-IN CONNECTION FORMING A RELEASABLE OPERATIVE CONNECTION WITH AN ANNULUS FORMED BETWEEN SAID SURFACE CASING AND SAID CONDUCTOR PIPE. 